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DRV10964: PWM Clarification

Mitchell
Expert 4915 points
Part Number: DRV10964
Other Parts Discussed in Thread: DRV10975

Hi Team,

My customer is currently evaluating the DRV10964 for use in an application that calls for very tight phase locked control of the motor to an external reference (+/-40ns). They have implemented this on past products using an FPGA to implement a phase detector, digital compensation and control output to the motor. The feedback to the phase detector is a 60Hz signal derived from the motor. In this implementation I have very fine resolution to the BLDC control, on the order of 6E-5 Hz/count.

In trying to implement this design using the DRV10964 they are running into issues allocating the gains in the loop and just realized that the input to the DRV10964 is digitized (with 9-bits) and is not an analog input. So they are starting to think that the DRV10964's PWM architecture may not be the best fit. Can you provide more detail of the PWM processing portion of the DRV10964 to help in this decision? (Filter bandwidths, discrete timing, etc.).

Also, do we have any similar drivers that accept an analog input without internal discretization?

Thanks,
Mitchell

  • 0
    TI__Intellectual 2600 points
    Mitchell,

    You are correct. DRV10964 digitizes the PWM duty cycle with 9 bits of accuracy (~0.2% resolution). In addition there is a filter on changing the speed command. The filter takes a step function 0 to 100% duty cycle and slows it to take 80 msec to make that transition. Smaller steps will scale linearly.

    I assume that you are looking for a 5V motor driver with relatively low current drive. All of our integrated control BLDC drivers (DRV10x family) have a similar digitization of the PWM input. Some of them do allow for an analog input, but it get's converted to the same 9 bits of resolution. Some of the other devices can change the slew rate applied to the input PWM command so if that is the limitation then we might have some options (DRV10975 is where I would start first).

    Let me know if there is more details I can provide.

    Thanks,
    Brian